See posted comments (0) Post a Comment Okavango Delta and Lake Ngami

Botswana

The vast stretches of grassland, wetland, and open water of the Okavango Delta are home to a variety of wildlife and vegetation as well as several native tribes. Although the Okavango ecosystem is considered one of the wonders of the world and attracts tourists from all over the globe, it faces several significant threats. Proposed upstream water projects are among these threats. The Okavango River originates in the highlands of east-central Angola and brings the flood waters and sediment necessary to maintain the dynamic flooding of the delta. Upstream dams could trap much of this sediment, causing the river View detailed information

See posted comments (0) Post a Comment Kangerdlugssuaq Glacier

Kangerdlugssuaq, the largest outlet glacier on Greenland’s east coast, is one of 12 fast flowing outlet glaciers that discharge ice into the surrounding oceans. Its rate of flow more than doubled between 2000 and 2005 reaching a speed of 14 km per year or 1.6 meters per hour. It has since slowed. During this same period mean summer temperature at coastal weather stations along southeastern Greenland increased 1.1° C. While the mechanisms controlling the rate of flow are complex and not fully understood, there is a general consensus that warming temperatures are driving the increased rates of discharge. The fronts of glaciers throughout southeast Greenland also receded rapidly during this same time period; an average retreat of 24 m/yr increasing to an average of 175 m/yr. Kangerdlugssuaq Glacier, which had been retreating 25 to 100 meters per year in the period between 1992 and 2000, retreated more than 4 km between April 2004 and April 2005. The loss of the Greenland Ice sheet is a major factor in projecting the sea level rise which might result from global warming. Loss of the entire sheet would raise global sea level an estimated 7 meters. If melting were the only mechanism through which Greenland was losing ice mass, this could take 1000s of years. The acceleration of Greenland’s glaciers raises concerns that the global sea level may rise more rapidly under global warming scenarios than had previously been estimated. View detailed information

See posted comments (0) Post a Comment Mendenhall Glacier

Mendenhall Glacier flows 22 kilometers from an elevation of nearly 1,600 meters in the Coast Mountain Range, to just above sea level at its terminus roughly 5 kilometers northeast of Juneau, Alaska. It has been receding since the 1700s when the “Little Ice Age” ended, retreating approximately 3 kilometers in the past century. Most of this retreat occurred in the mid-1940s and the late 1990s. The majority of the global community now accepts fluctuations in glaciers, particularly changes in their volume, to be reliable indications of a global trend of warmer air temperatures. While the retreating tongues of glaciers are less directly linked to climate change than overall volume, they are much more readily observed and allow the study of glaciers which would otherwise be out of the reach of most research projects. It is believed that the current climate conditions will not be reflected in most glacier tongues for years and will eventually amount to a kilometer or more of additional retreat. If climate conditions continue to follow current trends many glaciers will disappear completely. The satellite images from 1986 and 2007 show the continuing retreat of Mendenhall Glacier. Similar changes are taking place in many of the glaciers in southeastern Alaska. A 2002 study estimated the contribution of melting Alaska glaciers to sea level rise between the 1950s and 1990s to be twice that of the melting of Greenland’s ice sheet during the same time period. View detailed information

See posted comments (2) Post a Comment Great Man-made River Project, Al Kufra

Libyan Arab Jamahiriya

In the 1950s, oil exploration in Libyan Arab Jamahiriya turned up another resource beneath the scorching sands: the Nubian Sandstone Aquifer System. Radiocarbon analysis showed that some of the water in the aquifer system was 40 000 years old. Tapping the aquifers was chosen as the most cost-effective option for meeting the country's water needs. In 1993, Phase I of the Great Man-made River (GMMR) Project brought water from eastern well-fields at Sarir and Tazerbo to Benghazi (not shown). In 1996, Phase II brought water from well-fields at Jebel Hassouna to Tripoli (not shown). Phase III is still under construction. The project's largest reservoir, known as the Grand Omar Mukhtar, is located at Suluq (2006 image, yellow arrows). When fully operational, the GMMR will pump 3.6 million cubic metres of the Nubian Aquifer water per day. Water from the aquifer is used to support extensive centre-pivot irrigation agriculture at Al Kufra (see 1972 and 2001 images above). At current extraction rates the Nubian Sandstone Aquifer System is not likely to be depleted for a thousand years. Nevertheless, it is shared among four African nations: Libyan Arab Jamahiriya, Chad, Sudan, and Egypt. The concern of environmentalists is that eventually people will drain the aquifer faster than nature can renew it. The International Atomic Energy Agency is trying to bring the four countries together to plan rational shared use of the water. View detailed information

See posted comments (0) Post a Comment São Tomé

Sao Tome and Principe

São Tomé is the capital city of the island that shares its name. Located in the island's Agua Grande district, the population of São Tomé increased from a mere 8 431 in 1940 to 51 886 in 2001. The satellite image shows how settlements, especially along roads, have expanded inland from the city. While much of the island still retained its natural vegetation in 2007, vegetation loss is obvious near the capital city and surrounding settlements, where forests have been converted to croplands. Substantial oil reserves have recently been discovered off the island of São Tomé, which will most likely fuel increased development. View detailed information

See posted comments (0) Post a Comment Anjouan Island

Comoros

Comoros’ population quadrupled between 1950 and 2000. On Anjouan Island, where population density is 446 people per square kilometre, agricultural land is in short supply and many areas of steep terrain not suitable for agriculture have nevertheless been cultivated. Traditional agriculture leaves many trees in the fields, which help control soil erosion. However, pressure for food production is leading to more open field agriculture and some monoculture farming on the island of Anjouan. These more intense methods of agriculture encourage soil erosion. The top image above shows Anjouan’s fragmented forest. The reddish yellow areas on the simulated 3-D images show agricultural lands on Anjouan’s slopes. As a whole, Comoros lost about 60 per cent of its forest cover between 1950 and 1985. View detailed information

See posted comments (1) Post a Comment Coral Reefs of Mauritius

Mauritius

Over the past 50 years, the population of Mauritius has nearly doubled, to 1.2 million. It currently has the highest population density of any African country, 652 people per km2. Mauritius has also seen a dramatic growth in its economy, which has increased demands on its environment. Coral reefs almost surround Mauritius. Coral reefs are complex ecosystems, rich in biodiversity yet only able to survive in very clear, warm and nutrient-poor ocean waters. In these satellite images, coral reefs (yellow arrows) form a fringe along the island's shores and create shallow lagoons that are extremely important to the fishing and tourist industries. The island's population density as well as agricultural runoff, untreated sewage, changes in freshwater runoff, tourist activity, and global warming all threaten the health of the reefs. View detail information